Oxide Semiconductor Sidewall Channel for High-Resolution Displays
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Solution Overview
Problem
Display devices face challenges in achieving high on-current and numerical aperture due to limitations in transistor mobility and off-current, particularly with amorphous silicon and low-temperature polysilicon transistors, which restrict their use in high-resolution and high-frame-rate applications.
Innovation Solution
A display device structure incorporating an oxide semiconductor layer with a ring-shaped channel region, optimized by controlling the thickness and tapering angle of the insulating layer, and using transparent conductive layers to enhance channel length and reduce off-current, allowing for increased on-current and higher numerical aperture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a transistor channel is formed of amorphous silicon to enable low-temperature processing and simple structure, then manufacturing complexity is reduced and glass substrate compatibility is improved, but mobility is insufficient for driving circuit applications
Solution Approach 1:
The patent changes the material parameter from amorphous silicon to oxide semiconductor, which maintains low-temperature processing capability while significantly improving carrier mobility. This parameter change resolves the contradiction by achieving both ease of manufacture and high mobility through material selection rather than structural modification.
2Speed
If a transistor channel is formed of low-temperature polysilicon or single crystalline silicon to increase mobility for driving circuit use, then transistor mobility is improved, but manufacturing complexity increases and high-temperature processing is required
Solution Approach 1:
The patent changes the material parameter to oxide semiconductor, which inherently provides high mobility comparable to crystalline materials while maintaining amorphous structure that enables simple low-temperature manufacturing processes. This resolves the contradiction by decoupling mobility from crystalline structure requirements.
Solution Approach 2:
The patent employs oxide semiconductor as a composite material solution that combines the high mobility characteristics of crystalline semiconductors with the manufacturing advantages of amorphous materials, achieving both high performance and ease of manufacture through material composition rather than structural complexity.
3Ease of manufacture
If conventional semiconductor materials are used in selective transistors, then transistors can be manufactured with existing processes, but off-current is too high to maintain applied voltage for long periods
Solution Approach 1:
The patent changes the material parameter to oxide semiconductor, which possesses inherently low off-current characteristics due to its wide bandgap and stable electrical properties. This maintains compatibility with existing low-temperature manufacturing processes while dramatically improving voltage holding capability and reliability for display applications.
4Power
If transistor channel length is increased to provide higher on-current for high-resolution displays, then on-current is improved, but device area increases reducing numerical aperture
Solution Approach 1:
The patent changes the material parameter to oxide semiconductor, which enables higher carrier mobility and thus higher on-current density. This allows the transistor to achieve the required on-current with a smaller channel area, resolving the contradiction by improving current capability through material properties rather than increasing device dimensions.
Data Source
AI summary
A display device includes a substrate, a first insulating layer having a first side wall, an oxide semiconductor layer on the first side wall, a gate electrode facing the oxide semiconductor layer, a gate insulating layer between the oxide semiconductor layer and the gate electrode, a first transparent conductive layer between the oxide semiconductor layer and the substrate, the first transparent conductive layer being connected with a first portion of the oxide semiconductor layer, a first electrode on the first insulating layer on the side opposite to the substrate, the first electrode being connected with a second portion of the oxide semiconductor layer, and a second transparent conductive layer connected with the first transparent conductive layer, the second transparent conductive layer forming the same layer with the first transparent conductive layer.